text: Ampicillin has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against gram-positive organisms such as staphylococci and streptococci. Ampicillin (originally branded as "Penbritin") also demonstrated activity against gram-negative organisms such as H. influenzae, coliforms, and Proteus spp.